Vize Castle is more a hilltop ruin than a castle visit, but it gives the town its shape. The acropolis walls are usually dated to the Roman period, with later Byzantine rebuilding, and the surviving towers and wall fragments sit among pines above the mosque and main street.
Come for context rather than spectacle. From the hill you can see why ancient Bizye mattered: it controlled a route through the low Thracian country toward the Istranca foothills and the Black Sea.